llvm-link takes several LLVM bytecode files and links them together into a
single LLVM bytecode file. It writes the output file to standard output, unless
the -o option is used to specify a filename.

llvm-link attempts to load the input files from the current directory. If
that fails, it looks for each file in each of the directories specified by the
-L options on the command line. The library search paths are global; each
one is searched for every input file if necessary. The directories are searched
in the order they were specified on the command line.

Add the specified directory to the library search path. When looking for
libraries, llvm-link will look in pathname for libraries. This option can be
specified multiple times; llvm-link will search inside these directories in
the order in which they were specified on the command line.